The present invention relates to tracking and monitoring the intermodal movement status of mobile assets such as cargo containers.
Mobile asset management is a major concern in various transportation industries such as trucking, railroad and rental cars. In the trucking industry, the asset manager has to keep track of the status and location of each tractor and trailer in a fleet. The asset manager should also know whether each asset is in service (i.e., being transported by a tractor or other means) or out of service (i.e., not being transported by a tractor or any other transportation means). The asset manager should have similar information with respect to whether each tractor in the fleet is hauling a trailer or is not, and thus available for service. The asset manager should also be able to monitor the progress of each tractor and trailer according to plan for scheduling purposes.
Systems for tracking and monitoring mobile assets for fleet management are generally known. These systems typically include various sensors and communication units. Trucking companies usually install the sensors and communication units on the mobile units, e.g., the tractor or cargo trailers. The sensor determines the status and location, checks for proper operating conditions and any misuse, and monitors the progress of each tractor and coupled trailer for scheduling and security purposes.
In the transportation industry, it is also common for a trailer to be moved by railroad cars, known as piggybacking. When this happens, there is no tractor hauling the trailer, and thus no driver. As a result, there is a lack of security that the driver normally provides when the tractor is hauling the trailer. In addition, since the tractor equipped with tracking and monitoring system devices is not coupled to the trailer, the owner of the trailer loses visibility of the trailer""s location and status while the trailer is in transit on railroad cars. Although some railroads provide status messages to the owners of trailers, this is not always available or reliable.
There is a need to monitor equipment and shipments when intermodal move is in progress, i.e., in transit by rail. In addition, there is a need for frequent location reports of the trailers during such a transit for more efficient asset management.
The present invention is a system for tracking and monitoring the intermodal status of cargo trailers. The system of the present invention uses various asset tracking and monitoring sensors on a trailer, including a location determining sensor and a wheel movement sensor. The present invention determines the intermodal status of the trailer with a high level of reliability. In addition, the system of the present invention can be incorporated with existing complete cargo tracking systems to provide the intermodal status information with other monitoring and reporting features.
The system includes a sensor for providing data relating to the movement of the trailer and a wheel monitoring unit for monitoring the status of the trailer wheels. Wireless radio communication equipment transmits the trailer movement and wheel information data to a central station. A communications system, such as a cellular telephone system or paging system, is used to provide the wireless data links required between the trailer and central station. The central station receives the trailer information data and inputs the data to a processor. The processor determines the intermodal movement status using the trailer movement and wheel rotation data.
More specifically, the processor receives location or velocity information from the location sensor in combination with wheel rotation information, in particular whether there is rotation of the wheels or not. For example, if the location sensor indicates that the trailer is moving, but the wheel monitoring unit indicates that the wheels are not rotating, then the processor determines that an intermodal move is in progress. In contrast, if the location sensor indicates that the trailer is moving and the wheel monitoring unit indicates that the wheels are rotating, the processor determines that an intermodal move is not in progress. In addition, since an intermodal move is not in progress, the processor can deduce that a tractor is coupled to the trailer and moving the trailer.
A Global Positioning System (GPS) unit is used to provide data relating to the location and/or velocity of the trailer. If successive location reports are available, then position changes in successive location reports may be used rather than using GPS velocity data.
Signal information indicative of the wheel rotation status can be provided by anti-lock braking systems that are standard on trailers. Alternatively, an independent wheel rotation sensor is used to provide wheel rotation status.
In accordance with the invention, appropriate filters are applied to the GPS movement data to assure that the trailer movement and wheel status information is accurate. As a result, intermodal status errors caused by a small change in trail movement and wheel rotation status are eliminated.